[45.01] Extended Red Emission in the Evil Eye Galaxy

A. Majeed, A.N. Witt (U. Toledo), T.A. Boroson (KPNO)

The Evil Eye galaxy (NGC 4826; M64) is distinguished by an
asymmetrically placed, strongly absorbing dust lane across
its prominent bulge. We obtained a long-slit spectrum (KPNO
4-m; 5000 Å\ to 9500 Å) of NGC 4826, with the slit
across the galaxy's nucleus, covering equal parts of the
obscured and the unobscured portions of the bulge. By
comparing the spectral energy distributions at corresponding
positions on the bulge, symmetrically placed with respect to
the nucleus, we were able to study the wavelength dependent
effects of absorption, scattering, and emission by the dust,
as well as the presence of ongoing star formation in the
dust lane.

We report the detection of strong extended red emission
(ERE) from the dust lane within about 15 arcsec distance
from the nucleus of NGC 4826. The ERE band extends from 5400
Å\ to 9400 Å, with a peak near 8800 Å. The integrated
ERE intensity is about 75 % of that of the estimated
scattered light from the dust lane. The ERE shifts toward
longer wavelengths and diminishes in intensity as a region
of star formation, located beyong 15 arcsec distance, is
approached.

We interpret the ERE as originating in photoluminescence by
nanometer-sized clusters, illuminated by the galaxy's
radiation field, in addition to the illumination by the
star-forming complex within the dust lane. When examined
within the context of ERE observations in the diffuse ISM of
our Galaxy and in a variety of other dusty environments such
as nebulae, we conclude that the ERE photon conversion
efficiency in NGC 4826 is as high as found elsewhere, but
that the size of the nanoparticles in NGC 4826 is about
twice as large as those thought to exist in the diffuse ISM
of our Galaxy.

If the author provided an email address or URL for general inquiries, it is a
s follows: